What’s Vulnerable › Vulnerabilities

CVE-2020-15237: Timing attack in Shrine

• Severity: medium (CVSS 5.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.0% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-10-05 · updated 2026-06-17
• Weakness: CWE-203

Description

In Shrine before version 3.3.0, when using the `derivation_endpoint` plugin, it's possible for the attacker to use a timing attack to guess the signature of the derivation URL. The problem has been fixed by comparing sent and calculated signature in constant time, using `Rack::Utils.secure_compare`. Users using the `derivation_endpoint` plugin are urged to upgrade to Shrine 3.3.0 or greater. A possible workaround is provided in the linked advisory.

Affected products

• shrinerb shrine: before 3.3.0 — fixed in 3.3.0

How to fix

Upgrade to a fixed version: shrinerb shrine 3.3.0. Check the vendor advisory for mitigations.

References

• https://github.com/shrinerb/shrine/commit/1b27090ce31543bf39f186c20ea47c8250fca2f0
• https://github.com/shrinerb/shrine/security/advisories/GHSA-5jjv-x4fq-qjwp
• https://github.com/shrinerb/shrine/commit/1b27090ce31543bf39f186c20ea47c8250fca2f0
• https://github.com/shrinerb/shrine/security/advisories/GHSA-5jjv-x4fq-qjwp

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